Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as they travel from an outer suction port toward a center discharge port. An electric motor is provided which operates to drive the orbiting scroll member via a suitable drive shaft affixed to the motor rotor. In a hermetic compressor, the bottom of the hermetic shell normally contains an oil sump for lubricating and cooling purposes.
Scroll compressors depend upon a number of seals to be created to define the moving or successive chambers. One type of sealing which must be created is the sealing between opposed flank surfaces of the wraps. This flank sealing is created as a line seal adjacent to the outer suction port and the line seal travels radially inward along the flank surface due to the orbiting movement of one scroll with respect to the other scroll. Additional sealing is required between the end plate of one scroll and the tip of the wrap of the other scroll. Axial biasing of one scroll with respect to the other urges the tips of the wraps into engagement with the opposite end plate to enhance the sealing between the tip and the end plate.
The orbital movement of one scroll with respect to the other can be accomplished by having an electric motor drive on one of the scrolls. The electric motor normally includes a motor stator which is secured within a shell. A motor rotor and drive shaft are located within the motor stator for rotation with respect to the motor stator. A lower bearing housing and an upper bearing housing which are secured to the shell, rotatably support the drive shaft and the motor rotor within the motor stator.
The upper or main bearing housing includes a bore which locates a bearing which rotatably supports the shaft. The upper surface of the main bearing housing acts as a thrust surface for one of the scroll members and thus forms a reaction surface for the biasing load being exerted on this scroll member by the opposite scroll member. The multi-function role of the main bearing housing requires extensive and precision machining of the bearing housing to ensure its proper function within the compressor.
Prior art main bearing housings were machined using multiple machines and multiple setups. First, the hub portion of the main bearing housing was machined on its exterior surface and possibly a portion of its interior surface. This machining then provided a locating point for the remainder of the machining. The main bearing housing would be removed from the first machine after the first operation and transferred to a second machine using the first machined surface as a locating surface. The remainder of the machining was then performed on the main bearing housing. The multiple machines and multiple setups required for the machining of the prior art main bearing housing added costs and complexities to the production of the main bearing housing and thus the compressor.
The present invention provides the art with a scroll compressor which incorporates a main bearing housing that can be totally machined from one set up. This single set up machining eliminates a large portion of the tolerance stack-up as well as a significant amount of machining. This single set up also eliminates the problems associated with multiple machining operations and the multiple set ups for the main bearing housing. The elimination of machining set ups and the elimination of machining operations significantly decreases both the manufacturing complexities and the manufacturing costs for the main bearing housing and the scroll compressor while simultaneously providing a more accurate finish product.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.